A large number of technologies concerning a modified rubber for a rubber composition using silica or carbon black as a filler have been conventionally developed in order that a rubber composition having low heat generating property may be obtained. Of those, in particular, the following method has been proposed as an effective method (see, for example, Patent Literature 1 or 2). A polymerization active site of a conjugated diene-based polymer obtained by anionic polymerization involving using an organic lithium is modified with an alkoxysilane derivative containing a functional group that interacts with a filler.
Compounding a reinforcing filler into a rubber composition using a modified polymer obtained by the production method can secure low heat generating property. However, abrasion resistance when silica is applied to the reinforcing filler has still been insufficient.
In recent years, however, a request for a reduction in the fuel consumption of an automobile has started to become more and more stringent in relation to a social demand for energy savings and a global trend toward carbon dioxide emission control in association with the growth of interests in environmental problems. Accordingly, there have been growing requests for improvements in the low heat generating property and abrasion resistance of a rubber composition, and hence additional development has been requested.